Pawl-and-ratchet mechanism for electric clocks.



No. 729,253. PATENTED MAY 26, 1903. A. BARR, W. STROUD & L. BECKER. PAWLAND RATCHET MECHANISM FOR ELECTRIC CLOCKS.

APPLICATION FILED FEB. 6, 1901.

N0 MODEL. 4 SHEETS-SHEET 1- No. 729,253. PATENTED MAY 26. 1903. A. BARR,w. smoun & L. BECKER. PAWL AND RATGHET MECHANISM FOR ELEGTRIG CLOCKS.

APPLICATION PILEDIEB. 5, 1901.

I0 MODEL. 4 SHEETS-SHEET 2.

No. 729,253. PA'TENTED MAY 26, 1903. A. BARR, W. STROUD & L. BECKER.

PAWL AND RATGHET MECHANISM FOR ELEGTRIG CLOCKS.

APPLICATION FILED FEB. 6, 1901.

4 SHEETSSHEET 3.

N0 MODEL.

No. 729,253. PATENTEDMAY 26, 1903.

' A. BARR, W. STROUD & L. BEOKE PAWL AND RA'IGHET MECHANISM FOR ELECTCLOCKS.

PPLIOATION FILED 1'33. 5, 1901.

N0 LODEL. v 4 SHBETS-8HBBT 4- UNITED STATES Patented May 26, 1903.

PATENT OFFICE.

ARCHIBALD BARR, OF GLASGOW, SOOTLAND,-VVILLIAM STROUD, OF LEEDS,ENGLAND, AND LUDWIG BECKER, OF GLASGOW, SCOTLAND.

PAWL-AND-RATCHET MECHANISM FOR ELECTRIC CLOCKS.

SPECIFICATION forming part of Letters Patent No. 729,253, dated May 26,1903-.

Application filed February 5, 190 1 Serial No. 46,101- (NO m m To allwhom it nutty concern.-

Be it known that we, ARCHIBALD BARR,pIO

tric clocks which are dependent for their action on receiving electriccurrents periodically from a transmitting instrument. The type ofinstrument to which the invention refers contains a ratchet-wheel whichis prevented from turning backward by a retaining-pawl, anarmature-lever actuated by an electromagnet, and a driving-pawl pivotedto the lever. When the armature is attracted and again released, thedriving-pawl moves backward and forward over the periphery of the wheelthrough a distanceslightly greater than the pitch of the teeth and movesthe wheel forward tooth by tooth. So far the ratchet-wheel is free tomove forward under externally or internally applied forces, forinstance, by its own inertia or want of balanc ing of the moving parts.

Our invention consists in applying to the wheel a mechanical devicewhich will perfectly control its step-by-step movement when the wheel isactuated by the lever, but which will prevent it not only in the twoextreme positions of the'lever, but in all the intermediate positions,from moving a step, owing to other forces applied externally orinternally to the wheel.

Figure 1 is a front elevation of our device. Figs. l 1, and 1 are detailviews. Fig. 1 is a side elevation of the device shown in Fig. 1.

Fig. 2 is a side elevation of a modified form. Fig. 3 is a sideelevation of still another modification. Fig. 4 is a side elevation of amodified form of an armature-arm. Fig. 5' is a side and Fig.5 is an endelevation of a modification, showing a backward-and-forward movement ofan indicator.

The following is a'description of the action of the locking device:

L, Figs. 1, 12'1", 1, is the lever turning on the axis P, and it drivesthe wheel W by means of the driving-pawl D.

B and F are stops which limit the motion of L. t

H is the retaining-pawl.

The lever L carries a stop I, whose action on the wheel and theretaining-pawl constitutes the invention.

In what follows we shall call the forward motion of the lever that whichhas the same direction as that of the wheel and the forword position ofthe lever that which ends the forward motion.

In the forward position of the lever, Fig. 1 the stop I lies against theback of a tooth of the wheel and prevents it from moving forward. Tomake it impossible that a forward pressure applied to the wheel pressesthe lever aside and then moves the wheel forward, we make the line drawnperpendicular to the lower surface of the stop I and to the back of thetooth at the place where the two surfaces touch pass through (or inpractice near to) the axis of rotation of the armature lever. When thelever moves backward, the stop I at first acts in the forward position.Before the edge of the stop I moves clear of the tooth and also in allthe succeed- .ing positions of the lever until the backward posit-ion isreached the wheel is locked by the same stop I, in conjunction with theretaining-pawl H, Fig. 1 The retaining-pawl H, which prevents thebackward motion of the wheel, is placed below the stop I, and the lattermoves at such a distance above the end of the retaining-pawl that itdoes not allow the pawl to rise sufficiently to clear the teeth ofthe'ratchet-wheel. Forces acting on the wheel and tending to turn itonward will move the wheel less than the pitch of the teeth unless thestop I, and with it the lever, be pressed forward. The lever, however,cannot be pressed aside by such forces if the line joining the axis ofrotation ofthe lever and the place of contact between the stop I and theretaining-pawl H be at right angles, or nearly so, to the two touchingsurfaces-win, the

IOO

lower surface of the stop and the upper one of the retaining-pawl. Inpractice these surfaces can be planes at right angles to the linejoining their centers and the axis of rotation, Figs. 1, 1 and 1 Thestop I thus effectively locks the wheel in all the positions of thelever from its forward position to its back position. When the levermoves forward from its backward position, (at which the driving-pawl Dfalls into the next tooth,) the driving-pawl D moves the wheel onward,and the retaining-pawl is raised by the wedge-like action of the movingtooth. The stop I does not interfere with the rising up to a certainpoint of the retaining-pawl, owing to the play between the two at thebackward position of the lever, but the wheel is still locked by thestop I against forces acting on the wheel, since the retaining-pawlcannot rise sufficiently to clear the teeth. The breadth of the stop Iis chosen so that the stop I just clears the retaining-pawl when theforward edge of the stop has already entered the space between the nextteeth, Fig. l, and thus brings into action our first locking device.Finally the retaining-pawl falls into the next tooth, the lever arrivesat its forward position, and the stop I suddenly arrests the motion ofthe wheel.

"There is no position of the lever in which one or other of the lockingdevices does not act, and the wheel advances only one tooth, owing toone complete oscillation of the lever, although other forces, want ofbalance, or inertia are assumed to act on the wheel.

The application of this locking device to secondary electric clocks isshown in Fig. 1. L is the armature-lever, turning on the axis P. Itdrives the ratchet-wheel W by means of the driving-pawl D. B and F arethe back and forward stops which limit the motion of armature L anddefine that of D. H is the retaining-pawl, and I the stop which controlsthe motion of the wheel. The wheel W bears one hundred and twenty teeth,and the minute-hand is fixed on its arbor. The other wheels constitutethe ordinary hour-train.

The circuit of the electromagnet is closed and interrupted everyhalf-minute by a contact-making contrivance of the regulatingclock.

Other forms of our invention are shown in Figs. 2 and 3.

In Fig. 2 the driving-pawl D and the stop I, which is firmly fixed tothe frame of the clock, take the place of the stop I of Fig. 1. L, P, W,D, and H represent similar parts to those which they represent in Fig.l; but in this case pawl D is madea pulling instead of a pushing pawl,as in Fig; 1. In the forward position of the lever and also during thebackward motion the drivingpawl D lies against the fixed stop I andprevents the wheel from being turned. When the leverL moves into theback position, the forward motion of the wheel W is checked by the endof H coming in contact with the projection K on D, raising D until it isprevented from rising further by I. D, K, H, and I are so shaped andplaced relatively to the wheel W as to effectually prevent any motion ofW except that desired and caused by the motion of L.

A similar arrangement is shown in Fig. 3; but in this case the stop I iscarried by the armature-lever itself. The action of the difierent partsis similar to that described in connection with Fig. 2.

In turret-clocks and others where the hands are exposed to wind-pressureexternal forces are often thereby applied to the clock mechanism,introducing pressure on the stop. This pressure tends to prevent thefree motion of the armature-lever. In such cases we may arrange thearmature-lever in two parts, L and L Fig. 4, movable through a smallvangle relatively to each other, and we arrange the part L (which isacted on by the magnetic force) so that it is always free to move underthe actionof that force, and it is not influenced by the friction at theinertia and other stops. This part, having been set in motion by themagnetic or other driving force and having considerable inertia, comesin contact with the pin T or other part of the composite armature-leverwith a hammerlike action, setting it in motion and then carrying italong with it.

The clock may be arranged to take one step per minute or per half-minuteor other desired interval.

It will be evident that our apparatus may be used to indicate at adistance, by means of intermittent electric currents or impulses of amechanical, pneumatic, or other nature, signals other than those oftimeas, for ex ample, the transmitting of commands and of informationconcerning ranges on board a warship or in a fortress, or for indicatingthe height of the tide or of the water in a reservoir, or for indicatingat the steering-wheel of a vessel the position of the helm, or for theconveying of any other information which may be indicated by astep-by-step motion impartedto a hand upon a dial or an index upon ascale or other indicating device.

When it is necessary or convenient that the hand or other indicatorshould move either backward or forward, two ratchet mechanisms of thekind above described may be provided and connected to the pointer orother indicator through a mechanism of the kind known as a differentialgear. Fig. 5 represents such an arrangement. L and L are the twoarmature-levers, driving, respectively, the two ratchet-wheels W and Wby means of the two pawls D and D. One bevelwheel w of the differentialgear is pivoted on an arm ct, fixed to the spindle which carries thepointer P. L and L rotate W and W in opposite directions, and thepointer P rotates in one or other direction, according as the one IIO orother circuit of the electromagnets is closed and opened by hand or by asuitable apparatus.

Having thus described our invention, the following is what we claim asnew therein, and desire to secure by Letters Patent:

In clockwork mechanism applicable to secondary electric clocks and otherreceiving instruments, the combination with a ratchetwheel driven by alever and pawl, and a retaining-pawl locking said wheel against rotationin one direction, of a stop I fixed to the lever and engaging, in theforward position of the lever, a certain tooth of the wheel andrestricting, in the backward positions of the lever, the motion of theretaining-pawl, the stop and retaining-pawl being so shaped thatARCHIBALD BARR. WILLIAM STROUD. LUDWIG BECKER.

Witnesses:

JOHN LIDDLE, EDITH MARY EDMONDSTONE.

